This study was initially designed to test both the effectiveness of the enhanced CHW intervention and outreach system and the effectiveness of WHO PMTCT option B (vs. A) in ensuring successful PMTCT in the Tanzanian public-sector health system. However, in reaction to a report of non-compliance by the investigator team (incomplete records of written informed consent among PMTCT patients in the public-sector PMTCT clinics) the IRB at the Harvard School of Public Health decided to stop involvement in the option A vs. B component of this study. The IRB approved continuation of the enhanced CHW intervention and outreach system in the study.